Unless otherwise indicated herein, the description provided in this section is not itself prior art to the claims and is not admitted to be prior art by inclusion in this section.
A typical wireless network includes a number of base stations each radiating to provide coverage in which to serve wireless client devices (WCDs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped devices, whether or not user operated. In turn, each base station may be coupled with a switch or gateway that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a WCD within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other WCDs served by the base station.
Further, such a network may operate in accordance with a particular radio access protocol, examples of which include, without limitation, Orthogonal Frequency Division Multiple Access (OFDMA (e.g., Long Term Evolution (LTE) and Wireless Interoperability for Microwave Access (WiMAX)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), Global System for Mobile Communications (GSM), IEEE 802.11 (WIFI), BLUETOOTH, and others. Each protocol may define its own procedures for registration of WCDs, initiation of communications, handover between base station coverage areas, and other functions.
Each base station may provide wireless service to WCDs on one or more carrier frequencies (carriers), each of which could be frequency division duplex (FDD), defining separate frequency channels for downlink and uplink communication, or time division duplex (TDD), defining a frequency channel multiplexed over time between downlink and uplink use. Each carrier or its respective channels could be within a defined frequency band and could be of a particular frequency bandwidth, such as 5 MHz, 10 MHz, or 20 MHz for instance, defining a certain extent of air interface resources. A given base station could be arranged to serve a WCD on a single such carrier at a time or, with carrier aggregation service or the like, on multiple such carriers at a time.
Further, each base station in such a network may be communicatively linked with a signaling controller that carries out various network control functions, such as managing setup of bearer connections between the base station and one or more transport networks, tracking were WCDs are located in the network, paging WCDs, and the like. In addition, neighboring base stations may be communicatively linked with each other, to facilitate handover and other inter-base station signaling.
By way of example, in an LTE network, each base station (LTE evolved Node-B (eNodeB)) has a communication interface with a signaling controller known as a mobility management entity (MME), the base station and MME each also have a respective communication interface with a gateway system that provides connectivity with a packet-switched transport network, and the base station has a communication interface with each of its neighboring base stations. Typically, the nodes of such an LTE network would sit on a wireless service provider's core packet-switched network (e.g., a network compliant with the industry standard system architecture evolution (SAE) for the LTE protocol), and so the base station and each other network entity (e.g., MME, gateway, and neighboring base station) may each have an assigned Internet Protocol (IP) address on that network, and the interfaces between these entities may be defined as logical connections (e.g., established virtual tunnels) through that network.
In example operation, when a WCD enters into coverage of an LTE base station on a particular carrier, the WCD signals to the base station to initiate an attach process and to establish a radio-link-layer connection with the base station. In this process, the base station signals to the MME, the MME authenticates the WCD, the MME and base station obtain and store a context/profile record for the WCD, and the gateway system assigns an IP address to the WCD for use by the WCD to communicate on the packet-switched transport network. Further, at this point or later, the MME may engage in signaling with the base station and the gateway system to establish for the WCD one or more bearers for carrying packet data between the WCD and the transport network.
Once a WCD is so attached with a base station, the base station then serves the WCD on one or more carriers, managing downlink communication of packet data to the WCD and uplink communication of packet data from the WCD. For example, as the gateway system receives packet data destined to the WCD, the gateway system may forward the packet data to the base station, and the base station may schedule and provide transmission of that data to the WCD on the WCD's serving carrier(s). Likewise, as the WCD has packet data to transmit on the transport network, the WCD may transmit a scheduling request to the base station, the base station may schedule transmission of that data from the WCD on the WCD's serving carrier(s), the WCD may accordingly transmit the data to the base station, and the base station may then forward the data to the gateway system for output on the transport network.
Optimally, a wireless service provider will strategically implement base stations throughout a market area so that served WCDs can move between the base station coverage areas without loss of coverage. Each base station may include an antenna structure and associated equipment, and the wireless service provider may connect the base station by a landline cable (e.g., a T1 line) with the service provider's network infrastructure to enable the base station to communicate with a signaling controller (e.g., MME), gateway system, other base stations, and the like.
In practice, however, it may be impractical for a wireless service provider to run landline connections to base stations in certain locations. For instance, where a service provider seeks to provide many small coverage areas blanketing a market area or to fill in coverage holes between coverage of other base stations, the service provider may implement many small-cell base stations throughout the market area, but it may be inefficient or undesirable to run landline cables to every one of those small-cell base stations.
To connect a base station with the network infrastructure in such a situation, the wireless service provider may implement a wireless backhaul connection between the base station and another base station of the service provider's network. In this situation, the base station at issue operates as a relay base station, and the other base station operates as a donor base station. In practice, the relay base station includes or is coupled (e.g., via a local area network or other connection) with a WCD, referred to as a relay-WCD, and the donor base station then serves the relay-WCD in much the same way that the donor base station serves other WCDs. Further, the relay base station itself serves WCDs, in much the same way that any base station would.
With this arrangement, when the relay-WCD attaches with the donor base station, the relay-WCD may acquire connectivity and an IP address as discussed above for instance. But based on a profile record for the relay-WCD, the network (e.g., a signaling controller) may recognize that the relay-WCD is a relay-WCD (rather than a normal end-user WCD) and may therefore set up a bearer connection for that relay-WCD with a special core network gateway system (e.g., “SAE GW”) that provides for internal core network connectivity and assigns the relay-WCD with an IP address for use to communicate within the core network. Once the relay-WCD receives that core network IP address assignment, the relay-WCD may then convey that IP address to the relay base station for use by the relay base station as the relay base station's IP address on the core network. The relay base station may then operate as a full-fledged base station of the network, having IP-based interfaces with other core network entities (e.g., a signaling controller, a gateway system, and other base stations), albeit with those interfaces passing via the wireless backhaul connection provided by the relay-WCD, and via the core network gateway system.
Once the relay base station is thus in operation, the relay base station may then serve WCDs in the same way as a standard base station serves WCDs. Thus, when a WCD enters into coverage of the relay base station, the WCD may signal to the relay base station to initiate an attach process, the WCD may acquire an IP address, and an MME may engage in signaling to establish one or more bearers between the WCD and a gateway system. Each of these bearers, though, like the relay base station's signaling communication, would pass via the relay's wireless backhaul connection.